1. Field of Invention
The present invention relates in general to a driving circuit of a liquid crystal display, and more particular, to a driving circuit with chip-on-glass designed for use in a liquid crystal display.
2. Related Art
The liquid crystal displays, having the features of small volume, light weight, low driving voltage and low power consumption, have replaced the conventional cathode ray tubes applied to laptop computers, personal digital process systems and color television.
In a driving circuit of a typical liquid crystal display, multiple driving integrated circuit chips are packaged on one surface the corresponding tape carrier packages (TCP's). The TCP's are then electrically connected to the printed circuit board and the glass substrate of the liquid crystal display. In operation, control signals are transmitted from the printed circuit board to the integrated circuit chips of the TCP's. Being processed by the driving integrated circuit chips, driving signals are generated to the glass substrate.
However, as the material for forming the TCP's is very expensive, and tests for such package are relatively high, the package causes a great economic burden to the fabrication of liquid crystal display. Therefore, currently, the technique of chip on glass and wiring on glass (WOA) has been developed to construct the driving circuit of the liquid crystal display.
Referring to FIGS. 1 and 2, a top view of a liquid crystal display panel having the designs of chip on glass and wiring on array, and a local enlargement of FIG. 1 are illustrated, respectively. The liquid crystal display panel 100 includes the upper and lower glass substrates 102 and 104, and two sets of driving circuits. The first driving circuit includes a plurality of integrated circuit chips 106 packaged in the respective carriers 108 and electrically connected to the surface of the glass substrate 104. The second driving circuit is typically located at the side of the scanning circuit. The second driving circuit includes a plurality of integrated circuit chips 112a to 112c and a conductive wire 110. Each of the integrated circuit chips 112a to 112c has a plurality of solder pads. The conductive wire 110 is located on the glass substrate 104. The integrated circuit chips 112a to 112c are mounted on the conductive wire 110 on the glass substrate 104 via chip on glass technique. The conductive wire 110 serially connects the integrated circuit chips 112a to 112c and electrically connects to the integrated circuit chip 106 of the first driving circuit.
As the resistance of the conductive wire 110 is relatively high, different levels of voltage drops occur according to the length of the conductive wire when a driving voltage carried by the control signal is applied to the individual integrated circuit chips 112a to 112c via the integrated circuit chip 106, the carrier 108 and the conductive wire 110. As a result, the voltages applied to the integrated circuit chips 112a and 112c are uneven to affect the image quality.